1. Field of the Invention
The invention relates to a device for preventing the accidental erasing of a magnetic tape in a cassette when operating a cassette device.
2. Description of the Invention
It is well known that cassette, audio and video recorders are provided with devices which prevent an accidental erasing of the magnetic tape in a cassette when operating the cassette device. For example, in blank cassette tapes there is provided a recess in the back corners of the cassette having a fracturable member thereover. Pre-recorded tapes already have this member fractured. Once a desired recording has been made on the tape, fracturing the member covering the recesses will prevent re-recording or erasing the tape since the recorder will sense whether the recess is intact.
In this regard, for example, in German Pat. No. DE-PS 13 735 issued Mar. 21, 1974, provides for a cassette tape recorder which includes a device for preventing the accidental erasing of a magnetic tape contained in a cassette. For this purpose, two scanning levers scan the recesses provided in the cassette to determine if the recesses are open or still closed. A tension spring is provided and acts on the scanning lever and a plurality of rocker arms which are successively switched, so as to couple with an actuating lever which controls the operation of the device and thereby allows or prevents recording on the magnetic tape. Such a device, while desirable in many respects, is relatively expensive and not suitable for low cost devices.
Other arrangements utilize scanning levers fabricated out of plastic and include a spring which acts on the scanning lever and is formed as a single piece with the plastic scanning lever. While such a design provides for improved cost savings, unfortunately, it suffers the disadvantage in that the spring may become weak due to temperature influences, thereby hindering the scanning lever in performing its operation.